1. Field of the Invention
The present invention relates generally to printing presses and more particularly to a folder for a printing press.
2. Background of the Invention
Web printing presses print a continuous web of material, such as paper. In a folder of the printing press, the continuous web is cut into signatures and then folded. Various types of folders are known in the art, one of which is a combination folder.
Generally, combination folders incorporate a series of cylinders that uniquely provide functions to complete different portions of the fold, with each cylinder able to perform one or more functions. In order to provide for different types of printed products, the relative positions of cylinders within the combination folder may be altered. FIG. 1 shows the basic cylinder construction for a combination folder, for example a tucking cylinder. The basic cylinder shown herein is known in the art and is provided here for improved understanding of the present invention. A first function part 1, such as a tucking section, is mounted directly to a shaft 2 of the cylinder by a first arm 3 and a second arm 4. The shaft 2 supports a first hollow hub 5 and second hollow hub 6, which run concentric to the shaft 2. First and second hollow hubs 5, 6, in turn, support a third arm 8 and a fourth arm 9, which support a second function part 7, for example a gripper section. The shaft 2 and each hub 5, 6 can be driven by first and second drive gears 10, 11, respectively, which can be phased with respect to each other using helical gears.
Existing combination folders typically require a fold mode change and incorporate air cylinders to slide the helical gears to a required position. The helical gears, which are keyed to the main cylinder bodies, in turn, phase the cylinder bodies. This is incorporated to phase one set of cylinder bodies with respect to the other.
A drawback of the air cylinder and helical gear structure is that the helical gears may fail to shift, or seize, when changing relative position. This is due to the weight of the cylinder bodies or from the hubs freezing to the shaft due to lack of lubricant or due to fretting corrosion.
In order to reduce the likelihood of seizing, periodic maintenance is performed on the combination folder. However, the maintenance is time-consuming and increases the downtime of the folder.
U.S. Pat. No. 5,405,126 purports to disclose a folder having at least a first longitudinal folding device, driven severing members, and a second longitudinal folding device to which folding copies are supplied via a section of a conveyor belt which is disposed over a second loadable copy delivery. The folder comprises drawing devices disposed upstream of the severing members in the web-and-copy direction, first drive means for separately and controllably driving said drawing devices, and second drive means for driving said severing members and said cross-folding devices. The folder further includes a separate drive for driving said outwardly swingable conveyor belts. The second longitudinal folding device comprises components, and may include a phase-controllable separate electric motor for driving said components. The second drive means is an electric-motor drive. From one of the cutting or severing cylinders, the drive of the electric motor is transmitted to a gear. By means of the gear, the drive drives a folding cylinder, from there to a folding-jaw cylinder and then to a gripper cylinder. Furthermore, the drive of the second longitudinal fold can also be effected by the electric motor.
The ""126 patent has the disadvantage that the folding cylinder, folding-jaw cylinder, and gripper cylinder are driven by the same drive and, thus, adjustment and mode changes are difficult.
European Patent Application No. 0 699 524 A2 purports to disclose a printing unit with elements driven by dependent electric motors, identified by the letter M in the figures. Folding devices in figure twenty-two each have a separate motor that directly drives the folding cylinders in the folding devices. EP Patent No. EP 0 699 524 A2 has the disadvantage that one motor drives the folding cylinders of a folder, thus making phase changes difficult.
An object of the present invention is to provide for a device and method for simplifying group jaw adjustment and mode changes. An additional or alternative object of the present invention is to provide a multiple motor drive for a combination folder.
xe2x80x9cGripperxe2x80x9d and xe2x80x9cjawxe2x80x9d as defined herein can include any type of gripping device or holding device for a signature, such as an edge gripper or a jaw.
The present invention provides a folder comprising:
a first cylinder having at least one first gripper for holding signatures and at least one tucker for tucking the signatures to define a first fold;
a second cylinder having at least one first jaw interacting with the at least one tucker for holding the signatures at the first fold;
a first motor driving the at least one first gripper; and
a second motor separate from the first motor, the second motor driving the at least one tucker of the first cylinder and the at least one first jaw of the second cylinder.
With the two different drive motors, the phasing between the at least one first gripper and the at least one tucker can be altered through varying the angular relationship between the two motors, so as to set the fold location and thus the lap. No complicated gearing, clutches or air cylinders are required as in single motor devices. Moreover, the tuck-to-jaw relationship driven by the second motor is isolated from the first gripper and any cutting events, thus isolating torsional shock caused by the cutting. Tighter fold tolerances are possible.
Mode changes are also easier, as the motors can be altered to switch, for example, from a half-fold to a delta-fold.
The first motor also may drive at least one pair of cutting cylinders, and preferably two pairs of cutting cylinders, which may be connected by a phasing center to the first grippers. A phase between the cutting cylinders and the first grippers may be altered.
Preferably, the tuckers and the first jaws are connected by a phasing center for altering a phase therebetween. A group jaw adjust may phase the relative position of the jaws to the tucker.
The motors preferably are AC synchronous drives, which can make adjustments on the fly. One motor can be chosen as the main drive motor (reference), and the other motor changed with respect to the main motor.
In a preferred embodiment, the present invention provides a folder comprising:
cutting cylinders for cutting a web of material into signatures,
a first cylinder having at least one first gripper for holding the signatures at a lead edge and at least one tucker for tucking the signatures to define a first fold;
a second cylinder having at least one first jaw for holding the signatures at the first fold and at least one second jaw for holding the signatures at a second fold;
a third cylinder having at least one second gripper for holding the signatures at the first fold and at least one second tucker for forming the second fold;
a first motor driving the cutting cylinders and the at least one first gripper;
a second motor independent from the first motor, the second motor driving the at least one tucker of the first cylinder, the at least one first jaw of the second cylinder, and the at least one second gripper of the third cylinder; and
a third motor independent from the first and second motors, the third motor driving the at the one second law of the second cylinder and the at least one second tucker of the third cylinder.
The cut and grip action defines a first loop, the first tuck and first jaw and second grip defines a second loop, and the second tuck and second jaw a third loop.
With the three closed loops of the present invention the tuck to jaw relationship is isolated from the cutting cylinders, thus, the torsional shock to the gear train associated with the cut event is contained in the first drive loop. Moreover, variation in the fold normally attributed to the cut event is isolated, thereby, allowing tighter tolerances.
Preferably, each of the loops are synchronized with the other functional devices of the loops, for example, the first cutting cylinder pair, the second cutting cylinder pair, and the first gripper are synchronized with each other; the first tucker, the first jaw (second gripper), and the fourth gripper are synchronized with each other; and the second tucker and the second jaw (third gripper) can be synchronized with each other by virtue of a connecting gear train.
The second loop may phase with respect to the first loop, and the third loop may phase with respect to the second and first loop, so as to allow adjustments of the function devices of the different loops with respect to one another. Thus, lap adjustments and mode changes can be made without significant downtime. Phasing centers and idlers within the loops can provide for a further degree of freedom, for example a group jaw adjust. Different types of printed products can be accommodated. For example, by adjusting the lap, different lap distances can be accommodated, and by adjusting the group jaw, products of differing thicknesses can be manufactured. Mode adjustment, for example switching from a double-parallel fold to a delta fold, may also be accomplished by changing the angular relationship between the second loop and first loop and the angular relationship of the third and second loop with respect to the first loop.
The first loop may have a reference point, preferably the gripper, and all other functions and loops phase with respect to the reference point. Alternatively, the first and third loops could phase to the second loop, or the first and second loops to the third, however additional motion then is required as the print to cut would altered.
Preferably, one of the loops is removable for simpler folds, for example the third loop. Advantageously, removal of one of the loops simplifies the present invention, renders the present invention less susceptible to mechanical failure, and removes cost from an unwanted option.
All of the motors preferably AC synchronous motors providing power to the folder by connecting with one or more drive motor pinons. The AC synchronous motors provide the advantage of synchronizing the drive loops and providing power to the three drive loops. AC synchronous motors may also be uniquely associated with one of the functional devices, e.g., a first gripper spider gear, a first tucker spider gear, a second gripper (first jaw) spider gear, a third gripper (second jaw) spider gear, a second tucker spider gear, or a fourth gripper spider gear, thus, power can directly be applied to the function adjustment devices. By providing power directly to the functional, no extraneous parts are needed and less torque is lost through friction.
At least one of the motors preferably is supported directly a ground surface, so as to stabilize the position of the motor, hence, advantageously, the present invention is stabilized and angular mode changes are facilitated.
A motorized platform for changing the angular relationships between the first, second, and third loops may also be incorporated into the invention. The advantage thus provided is increased efficiency in mode changes and less operator intervention during the mode changes.
Phasing centers, i.e. two gear constructions having a compound gear between the two gears to alter a phase, and idler gears preferably are provided within the first, second and third loops to permit phasing between the elements within each loop.
In an alternate embodiment, the folder may include four independently driven motors, with one motor driving the cut cylinders, and another motor independently driving the first grippers. The second and third loops then each have a separate motor.
The present invention also provides for a method for cutting and folding printed products comprising the steps of:
driving with a first motor a first loop for cutting a signature and transferring the signature to a first gripper with a first motor;
driving with a second motor a second loop for tucking the signature into a first jaw and transferring the signature to a second gripper; and
driving with a third motor a third loop for tucking the signature into a second jaw.
Preferably, the method includes altering a phase between at least the first and second loops, so as to set a lap or perform mode change.
The phasing preferably is performed on the fly, thus, providing the advantage of reduced machine downtime.
The present invention also provides a folder comprising a first cylinder having a first functional device and a second functional device and a second cylinder having a third functional device dependent on the second functional device. A first motor drives the first functional device and a second independent motor drives the second and third functional devices.